Electrically driven vehicles have been proposed in which a vehicle driver performs a shift operation, when commanding a traveling mode including a vehicle stop for a, so-called, momentary type shifter which is, in a normal state, self reset to a reference position, operated from the reference position to one of positions of Neutral position (N), a forward (D) run position, and a reverse (R) run position, each of which corresponds to a desired traveling mode, so that a command in the above-described traveling mode is issued. Part of the above-described vehicles has already been put into practice.
At an instant time when the above-described shift operation is performed, the shifter issues a signal corresponding to the traveling mode that the vehicle driver desires (normally, an electrical signal). The vehicular traveling drive system is controlled in response to the signal from the shifter so that the vehicle can appropriately run by means of a dynamical power from the traveling drive system in a traveling mode (including the stop of the vehicle) that the vehicle driver desires.
Incidentally, the self-resetting shifter (momentary type) is shift operable with a slight force as compared with a shift lever normally used in an automatic transmission which mechanically commands the traveling mode. Hence, it often occurs that the shifter is kept operated from the reference position to other position according to a mere touch of an obstacle such as a book onto the shifter.
When the shifter is kept to be operated from the reference position to another position against an intention of the driver, the driver turns an activation switch such as an ignition switch to an ON state while the driver is not aware of it to switch the traveling drive system of the vehicle from the reference position to the other position in response to the state switching operation. Hence, since, as described above, the shifter is kept operated from the reference position to the other position, the vehicle is started in the traveling mode that corresponds to the operation position of this shifter.
However, the driver himself does not touch the shifter and is convinced that this shifter is placed at the reference position and the vehicle is not started even if the activation switch is turned to ON for the traveling drive system to be switched into the activation state. Hence, an occurrence of such a situation that a mere activation state of the traveling drive system due to the ON of the activation switch flusters the driver so that it is necessary to avoid this situation in terms of a safety driving.
In order to avoid the occurrence of the situation described above, it can be thought that use is made of a technique described in, for example, a Patent Document 1.
This proposed technique is an improvement proposal as described below for a range selection system of a shift-by-wire type in the automatic transmission.
The range selection system in the shift-by-wire type is such that the operation position of the shift lever by the vehicle driver is electrically detected and the motor is activated in response to the detection signal so that the automatic transmission is transferred into a range selection state that the vehicle driver desires.
Even in the shift-by-wire type range selection system, the shift lever of the self-resetting type (momentary type) is used. In this case, since this shift lever is shift operable with the slight force, the shift lever is kept operated from the reference position to the other position against the intention of the vehicle driver and the automatic transmission is forced into the range selection state that the vehicle driver does not desire.
In order to prevent such a situation as described above, Patent Document 1 describes that a shift allowance switch to be operated by the driver when the shift operation is carried out is additionally installed and unless the operation of the shift allowance switch and the operation of the self-resetting type (momentary type) shift lever are made almost concurrently, the automatic transmission is not switched to the range corresponding to the shift lever operation.
In a case where the same thought as the above-described measure is applied to the shift abnormality measure upon activation for the vehicle, a shift allowance switch is additionally installed. Even if the shifter is kept at the position different from the reference position, the switching is not carried out to the traveling mode corresponding to the present operation position of the shifter unless the driver manipulates this shift allowance switch.
Hence, the occurrence of the situation such that the vehicle is started against the intention of the vehicle driver at least when the shift abnormality occurs can be avoided.
However, if the measure described in Patent Document 1 is applied, an addition of the shift allowance switch is indispensable. In addition, it is necessary to provide a wire harness to transmit the signal from the shift allowance switch. Consequently, a high cost of the measure described above cannot be avoided.